Table 2. Percentages of children classified as underweight, poor infant weight gain, or obese according to the WHO Growth Standard (WHO) and the British 1990 Growth Reference (UK1990).
| ALSPAC | GMS | Combined:RR (95% CI) | |||
| WHO | UK1990 | WHO | UK1990 | ||
| Underweight | |||||
| 6–8 weeks | – | – | 3.6 | 2.9 | 1.12 (0.87 to 1.43) |
| 4 months | 2.0 | 2.4 | 2.1 | 2.4 | 0.86 (0.55 to 1.33) |
| 8 months | 0.7 | 2.6 | 0.7 | 1.8 | 0.30 (0.17 to 0.56) |
| 1 year | 0.3 | 2.4 | 0.4 | 2.5 | 0.15 (0.07 to 0.32) |
| 1.5 years | 0.6 | 2.9 | – | – | 0.22 (0.10 to 0.48) |
| Poor infant weight gain | |||||
| Birth to 1 year | 1.7 | 7.1 | 1.6 | 5.4 | 0.24 (0.16 to 0.36) |
| 6–8 weeks to 1 year | – | – | 0.4 | 5.4 | 0.08 (0.03 to 0.24) |
| Obese (%) | |||||
| 1 year | 8.7 | 2.7 | – | – | 3.26 (2.21 to 4.83) |
| 1.5 years | 8.0 | 2.6 | – | – | 3.11 (2.06 to 4.71) |
| 2 years | 7.5 | 4.3 | – | – | 1.74 (1.20 to 2.51) |
| 4–5 years | 7.2 | 5.0 | 10.1 | 8.4 | 1.35 (1.02 to 1.78) |
ALSPAC, Children in Focus sub-cohort of Avon Longitudinal Study of Parents and Children; GMS, Gateshead Millennium Baby Study; RR, relative risk for each outcome using the WHO standard, compared with the UK 1990 reference; Underweight, weight <2nd centile; Poor infant weight gain, conditional weight gain <−1.33 SD, equivalent to downward crossing through two major centile lines on each growth chart; Obese, body mass index >98th centile.